Devices for providing protection for electrical or electronic instruments against overvoltages, for example, resulting from lightning phenomena, are well known.
These protection devices generally comprise one or several components providing protection against overvoltages, for example, such as a varistor or a spark gap, provided with power supply terminals used to electrically connect them to the installation to be protected. When the protection components are exposed to voltages exceeding a predetermined threshold value, the protection components allow a discharge current to flow to earth while clipping the overvoltage to a value compatible with the resistance of the installation and the equipment connected to the installation. These components and devices are generally referred to as “surge arresters” or “lightning arresters”.
For obvious safety reasons, and particularly to limit risks of electrocution or short circuits, it is known that protection devices can be provided with an insulating box capable of electrically and mechanically separating the internal devices in the protection devices, such as the protection component, from the environment in which these protection devices are used.
In general, these boxes are standard sized adapted to modular use within standardised electrical switchboards.
An electrical connection interface is necessary between the outside and the inside of the box in order to be able to electrically connect the protection component to the electrical installation to be protected.
It is known that this can be done using connection pads at which an electrical junction can be made with a conducting element outside the box, such as a cable or a rail. In particular, the connection pads may be housed in the box, they may be accessible from the outside of the box through orifices formed in the box and include a mechanical clamping system using conducting jaws giving a secure locking of the electrical junction, for example, by screwing.
Moreover, it is necessary to electrically connect the protection components to the connection pads inside the box. This is usually done by providing the protection devices with connection elements making the connection between the power supply terminals of the protection components and the connection pads.
In general, these connection elements are in the form of a set of conducting strips or plates, preferably metallic.
It is known that permanent junctions such as built-in junctions can be used with various assembly methods to electrically connect a metallic strip to a connection pad, or several metallic strips to each other, within a lightning arrester.
The permanent junctions must be sufficiently large and the quality of the permanent junctions must be sufficiently good to resist mechanical and thermal stresses generated by the passage of discharge currents that can circulate through the protection component during normal operation of the protection device.
In particular, it is known that thermal assembly methods, such as electrical brazing or soldering, can be used, particularly spot welding or induction welding.
These assembly methods provide satisfactory results for the mechanical strength and electrical resistance of the junctions with regard to discharge currents; however, these assembly methods suffer from non-negligible disadvantages.
In particular, welding, soldering and brazing methods frequently require complex and expensive equipment and tooling that require regular maintenance, such as tunnel furnaces and wave soldering machines.
Furthermore, the use of some of these methods, for example, soldering with an iron, requires action by highly qualified operators. In this case, the assembly quality is dependent on the dexterity of the operator and, consequently, the reproducibility is uncertain.
Finally, welding, soldering and brazing operations frequently require the use of polluting substances such as lead, or irritating substances such as deoxidation fluxes, and these substances are potentially harmful to the environment and to the health of the operators making it essential to use complex and expensive protection systems for suction and treatment of the substances.